The present invention relates to the field of vehicular control systems, and more particularly to means of alerting the driver of a vehicle of a potential collision situation using passive techniques.
Interest in vehicular collision avoidance systems has been gaining recently, and some manufactures have begun offering collision warning systems in their vehicles. Such systems can be categorized as active, semi-active, and passive systems. Active systems involve inter-vehicular communications where vehicle systems in different vehicles communicate with each other, indicating their present location, speed, heading, and so on. These systems operate as an ad hoc network with a short or medium radio range. These systems are fairly complex and expensive, and do not provide information regarding vehicles which are not equipped with such equipment. Semi-active systems use active sensors such as short range radar, laser, or ultrasound detection to detect vehicles nearby. Signals are transmitted from the vehicle, and receivers detect reflections of the signals to determine distance and movement of surrounding objects. These systems are also fairly sophisticated and expensive. An example of a passive system is an optical detection system, which uses a camera to monitor areas around the vehicle, detect patterns corresponding to other vehicles, and determine distances and possible collision conditions. However, in inclement weather, optical systems have limited capabilities. Therefore there is a need for a relatively inexpensive alternative that is capable of detecting some collision situations and alerting drivers of a potential collision.